1. The Field of the Invention
The present invention relates to orthodontics, and more specifically, to a custom-fitted orthodontic bracket and associated methods and computer program products for manufacturing the orthodontic bracket.
2. Background and Related Art
An individual's jaw, gums and teeth (also referred to herein as an “orthodontic structure”) combine to provide a critical function by allowing the individual to mechanically break down food for safer swallowing and more efficient digestion. Sever malformations or mechanical flaws of the individual's orthodontic structure may also interfere (even if only slightly) with the proper articulation of language. The abilities to properly eat and speak fluidly are essential needs of mankind. Any degradation in these abilities may have a significant impact on the affected individual's quality of living.
Also, human beings have varying concerns about their own appearance and how they are perceived by others. In addition, some human beings are sometimes inclined (even if on a subconscious level) to form negative judgments about an individual if the appearance of the individual's teeth varies significantly from an ideal societal norm. Accordingly, individuals with such variances may desire for better conformance of the teeth with societal norms, whether their motivation be for the proper functioning of the orthodontic structure, or whether their motivation be for a better appearance, or a combination thereof.
Orthodontics is a now highly-advanced branch of medicine in which dental practices are implemented to manipulate a patient's orthodontic structure for better function and appearance. In order to perform such manipulation, it is necessary to apply sustained and appropriately-directed forces to the teeth. To apply such forces to the teeth, an orthodontist typically affixes brackets to a patient's teeth using bonding material. The orthodontist then couples an arched wire (often called an “archwire”) to the brackets using an archwire slot formed in each of the brackets. Some of the teeth may have the archwire anchored to the correspondence bracket, while other teeth may have brackets that allow for some sliding of the archwire.
In order to achieve movement of teeth towards a desired corrected position, it is not only necessary that sustained force be applied, but also that that force be properly directed to achieve the specific movement desired. This requires the considerable knowledge and expertise held by licensed orthodontists. The orthodontist will use that expertise to properly place the brackets, and to properly bend the arched wire. Despite such expertise, however, while the teeth may generally move towards the corrected position, there may be some slight errors in the forces applied by the arched wire that become apparent from the path of movement of the teeth. Accordingly, it is often necessary for the orthodontist to rebend and reposition the arched wire several times before correction is achieved.
One problem associated with orthodontic brackets is that teeth can have a substantially infinite variety of curvatures. Furthermore, precision fitting of the orthodontic bracket promotes higher bonding strengths of the bracket to the tooth. In order to get a good fit at the bracket tooth interface, the orthodontist conventionally identifies a particular position at which the bracket is to be affixed. The orthodontist then selects a bracket that has the closest base curvature match to the surface from amongst a number of pre-manufactured brackets having different base curvatures.
Since there is only a limited number of bracket base curvatures to select, and an infinite variety of tooth surface curvatures, a perfect match is often elusive. Accordingly, the bond strength between the bracket and tooth is not quite as strong as would be the case if there was a perfect match. Also, additional attention would be needed to fill in the gaps due to the imperfect match with a reliable bonding material such as a cement.
One advanced bracket manufacturing technology involves the formation of a custom-fitted bracket that fits with precision on the actual surface of a tooth. A three-dimensional representation of the current orthodontic structure is first acquired using, for example, a high resolution optical scanner. Then, the brackets are designed and optimally positioned in the computer using the three-dimensional representation. The brackets are then physically formed by first making the bracket form out of wax. For example, rapid prototyping techniques may be used to form such wax structures in layers 0.02 mm thick. A more rigid bracket may then be formed to have an identical structure as the wax structure.
This conventional custom-fitted bracket manufacturing technology allows for the positive formation of a custom-bracket that most often is easy to position since the bracket keys into the appropriate surface of the tooth by sense of feel. However, there are some disadvantages to this manufacturing technique. Specifically, the positive formation of brackets using rapid prototyping techniques can be quite expensive and time-consuming. Often orthodontists cannot afford rapid prototyping equipment so such manufacturing often needs to be performed by an off-site service. In addition, the higher costs associated with rapid prototype manufacturing of brackets is most likely passed onto the patient (or insurer) thereby making custom-bracket use relatively expensive.
Accordingly, what would be advantageous are alternative methods for manufacturing custom-fitted brackets that do not require the positive formation of the bracket.